Artificial leg



| J. LAMB ARTIFICIAL LEG Filed Nov. 1a, 1926- I N VEN TOR.

ATTORNEY Patented Sept. 18, 1928-.

UNITED STATES LESLIE J. LAMB, OF OAKLAND, CALIFORNIA;

ARTIFICIAL LEG.

Application filed November 18, 1926. Serial No. 149,094.

My invention relates to artificial legs for above-knee amputations and isdirected especially to the knee joints thereof.

It is an object of my invention to improve I '5 upon artificial legs of the well-known tubular type to increase their strength and rigidity withoutappreciably altering their light Weight. It is an object of my invention to overcome the objectionable quivering which occurs when a heavy man steps down from a curbing or other elevation, upon his artificial leg. It is an object of my invention to overcome the wobbling and feeling of instability and unsolidity which the wearer f the ordinary artificial leg istroubled with when arising fronra sitting position.

It is a further object of my invention to alter the effective point of support of the lower leg relative to its pivot and to its cen ter of gravity, to normalize the inclination of said lower leg at all times.

There must be auxiliary pivotal means connecting the lower leg to the leg-supporting harness in order to control the inclination of the lower leg, and it is an object of my invention to overcome the squeaks and noises which frequently are caused by this usual metallic connection. It is a further object of my invention to maintain. this con- 3H nection close to the main knee-hinge-pivot point, and to make its effective line of stress transmission as invariable as possible with altered leg inclinations.

ther and ancillary objects of my invention will be brought out in the following description, or will be suggested in the use of the device of my invention. Certain modifications from the device herein described in detail are possible Within the purview of. my invention,'and therefore, I desire to be circumscribed only within the limits set up by the claims finally determining my invention.

Referring to the drawings:

Figure 1 is a composite side elevation and median vertical section of the knee portion of ,an artificial leg incorporating my improvements; the major part of the figure being broken'away to disclose said section.

Fig. 2 is a composite front elevation and vertical section similar and at right angles to the view of Fig. 1. The plane and extent of section are indicated by the line 2-2 in Fig. 1.

Fig. 3 is a transverse sectional plan above the brace in the lower leg. tion is indicated by the line 33 in Fig. 1.

The plane of sec- Fig. at isa perspective view of the portion of the pivotal arm which incorporates the brace extending to the front wall of the lower leg.

The artificial leg consists of an upper limb portion 2 generally of hollow fibre adapted to receive the wearers limb stump, and is hingedly connected to the lower leg 4, also generally of hollow fibre. For convenience of description, the front wall of the lower' leg is differentiated by the reference character 6, and the rear wall thereof by the character 8. Theupper and lower extremities of the leg are purely of conventional character and do not form part of my invention, which is an improvement directed to the knee portion of the leg. It will be understood that an artificial foot is attached to the lower extremity of theleg, and that the straps 10, 12, and 14 terminate above the artificial leg in a harness for attaching'the artificial leg to the wearers body. r

The bottom 16, of the upper limb portion, is reduced in size to recess slightly into the lower leg 4, and carries the knee-hinge pin 18 journaled transversely therethrough. A pair of bearing lugs 20, 22 upstand one from each side of the lower leg 4-, to receive the ends of the pin 18, and pivotally support the lower leg from this pin.

Means are customarily provided for controlling the pivotal position of the lower leg relative to the upper leg. A crank arm 24L is journaled on the pin 18 with its long arm curving into contact with the rear wall 8 of the lower leg, and to which it is secured by a bolt 26. The strap 12 leading from the suspender or shoulder harness which supports the leg, terminates in a stirrup 28, the lower bar 30 of which, is a pin for pivotally attaching the harness to the arm 24. It will be understood, that although the strap 12 should at all times be taut enough to hold the artificial leg to the stump when the Wearers weight is off the leg, yet by connecting the stirrup to the arm 24% abaxially of the main hinge pin 18, the lower leg may be pivotally moved somewhat by increasing or de- 1 creasing the tension of strap 12. The hole 32 in backof the pin 18 in the arm 24:, was intended to receive the stirrup pin 30 for this purpose. A stop 34: on the arm 24, cooperates with the bottom of the upper limb portionat 36 to prevent reverse buckling of the knee joint.

By raising and lowering the harnessed shoulder as he Walked, the wearer might operate the lower artificial leg to simulate normal leg action. However, it is found that the normal tension of the strap 12 always keeps the lower leg inclined backward somewhat, causing the toe to drag when walking.

While shifting of the weight in walking naturally causes the leg to incline backward at the desired time, the difiicult thing is 'to straighten the leg to rigid position. A further disadvantage I endeavor to overcome by my improvement is entailed in the fact that the hole 32 is spaced so far from the pivotal axi s,that excessive shoulder motion is required to operate the lower leg.

I have provided means for attaching the stirrup 28 to the arm 24 in front of and very close to the main hinge pin 18, and I have purposely made this connection flexible and non-metallic. A leather strap 38 is secured to front of the arm'2sl by a screw 40. The upper end of the strap terminates in a loop 42to receive the stirrup pin 80, and a wire I 44 is looped horizontally around the strap between the screw 40 and the loop l2, and s fixed at. 32 to the arm 2%. The wire as permits free inward flexing ofthe strap 38, but limits its outward movement. Thus the line of force action never moves far from the hinge pin '18 no matter how far the lower leg is bent. A reinforcing bracket 46 is riveted to the arm 2st and has its outer end bowed to receive the depending looped end l8 of the strap 38. The bracket 46 is merely an attachment auxiliary to the single screw 40.

Looped straps a8 and 50 are riveted to opposite sides of the stirrup 28 and are adapted to receive the guy straps l0 and 14- for bracing the knee laterally to maintain the leg in a vertical plane. 7 y

The artificial leg is of light construction, and it is invariably found that the bearing lugs 20 and 22 sag enough to cause the arm 2st to transmit a certain amount of the wearcrs weight to the rear wall 8 of the lower leg. This produces an objectionable unbalance, and which unbalance is a most important object of my invention to overcome. The

situation is remedied by means of an auxiliary brace. -A metal strip 52 is bent into an elliptic bow 54, and its ends are brought together into a yo, 2 56 which straddles and is riveted to the mid-portion of the arm 24. The bow terminates in contactwith the front wall 6 of the lower leg, and is attached thereto by a bolt 58'. A diagonal strut 60 riveted between the strip 52, and the arm 24 completes hinge pin to the rear wall of the tu ular lower leg, a brace connecting the front wall of the lower leg to said arm, a flexible support secured to said arm in front of,immed1ately adjacent, and partially concentric, to the hinge axis, and pivotal means connecting. said support to said harness strap'to control the inclination of the lower leg. Y In combination with the knee hinge 0 an artificial leg, a control arm pivoted about the pin of said hinge and having an end thereof lined to the lower leg portion, an operating member for said arm secured thereto to extend upwardly therefrom forwardly of i said hinge pin, and means to maintain the effective lever arm of said operating member constant for the different angular relations of said legportions. V

3. In combination with the knee hinge of an artificial leg, a control arm pivoted about the pin of said hinge, said arm having an end thereof fixedly related to the lower leg por ortion of the other end thereof cylindrical .y curved about the tion and the forward pivotal axis of the arm, and a flexible extension member for said arm fixed thereto to extend longitudinally of the upper leg portion and arranged to maintain an engagement with the cylindrically curved surface of said second arm end.

4. In combination with an artificial leg" comprising a tubular upperlleg portion, a harness strap from said upper portion for securing the artificial leg to the Wearers leg stump, a lower leg portion, a hinge pivotally connecting said leg portions, a control arm connecting the hinge pm to the lower leg portion, a flexible support secured to sa d arm in front of and partially concentric to the hinge ax1s,'and means connecting said support to said strap. a

In testimony whereof I affix my signature.

LESLIE J1 LAMB. f 

